JP2015017700A - Actuator with progressive gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator for a vehicle grille shutter system, in which an output of a motor is more closely matched to a required output of the actuator.SOLUTION: An actuator for a grille shutter assembly of a vehicle has a motor connected to an output via a gear train. The output has a connection for connecting to louvers of the grille shutter assembly. The gear train has a gear ratio which is variable depending on an actuation angle of an output shaft. Optionally, a return spring is arranged to resiliently return the output shaft to an initial actuation angle when the motor is not active.

Description

  The present invention relates to an actuator, and more particularly, to an actuator of a grill shutter assembly (assembly) having a progressive transmission gear.

  Automatic grill shutters for adjusting the louver angle and thus the air flow are a more important component of automotive engine thermal management systems. Regulation is conveniently achieved by electromechanical actuators. The actuator is generally adapted to rotate the grill shutter louver via a gear train to change the size of the opening for the air flow to cool the radiator.

  Open loop operation of stepping motor actuators is a reliable prior art. However, a fail-safe mechanism (mechanism) needs to be integrated into the grill shutter actuator in case of power failure or in case of inaccurate louver positioning at stop. For example, the return spring can return the louver to its initial position (open or closed position as required). In this case, during operation, the actuator must always operate against some additional force applied to the spring force due to the intense air flow when the vehicle travels at high speed. This usually requires an oversized or overpowered electromagnetic motor to transmit the maximum torque in the maximum open (or closed) position. This also means that power consumption is high and does not match an effective environmentally friendly or “green” system.

  Accordingly, there is a need for an actuator for a vehicle grill shutter system in which the output of the motor more closely matches the output of the desired actuator. The present invention solves this problem with a progressive gear that compensates for variable torque demands.

  Progressive transmission gears or variable gears have long been known. A comprehensive description of the forward transmission gear is disclosed in US Pat. No. 2,061,322 or US Pat. No. 8,196,487. Progressive transmission gears for automotive applications are frequently found in steering systems.

US Pat. No. 2,061,322 US Pat. No. 8,196,487

  Accordingly, in one aspect, the present invention provides an actuator for a grill shutter assembly, including a motor having a motor shaft (shaft), and a connection for connecting the output shaft and the louvers of the grill shutter assembly. And an output section and a gear train (gear train) connecting the motor shaft to the output shaft, and the gear train has a variable gear ratio (gear ratio) according to the operating angle of the output shaft.

  Preferably, the gear train includes at least one progressive transmission gear.

  Preferably, the progressive transmission gear includes a first helical gear (spiral gear wheel) and a second helical gear meshing with the first helical gear.

  Preferably, the second helical gear is attached to the output shaft.

  Preferably, the first helical gear is connected to the motor shaft by at least one spur gear.

  Preferably, the first helical gear and the second helical gear have logarithmic pitch trajectories.

  Preferably, a return spring configured to elastically return the output shaft to the initial operating angle when the motor is not operated is provided.

  Preferably, the return spring is a coil spring disposed around the output shaft, the first end is fixed to the second torsion gear, and the second end is fixed to the support portion of the output shaft.

  Preferably, the motor is a stepping motor and is connected to a PCB having a control circuit for controlling the motor in response to a control signal.

  Preferably, the output unit includes two output shafts.

  Preferably, the connecting portion includes a non-circular socket formed at the output shaft or at the end of each output shaft, and is configured to receive the end of the corresponding operating shaft of the louver.

  The present invention allows for the assembly of an actuator for a grille shutter that has an output that closely follows the load, i.e., the operating requirements of the grille shutter, thus enabling a smaller and more efficient actuator for this application. Certain embodiments of the present invention allow for the assembly of failsafe actuators that can be utilized in open loop operation. This eliminates the need for a sensor system that detects the actual position of the grill shutter louver, which is necessary for conventional actuators, and reduces complexity and cost.

  Preferred embodiments of the invention are described below by way of example only with reference to the accompanying drawings. In the figures, identical structures, elements or parts that appear in more than one figure are designated by the same reference numeral in all appearing drawings. All dimensions of the parts and shapes shown in the figures are chosen for simplicity and clarity and are not necessarily shown in a certain ratio. The drawings are described below.

Figure 3 shows a typical linearly increasing torque-angle curve required by a grill shutter actuator. Fig. 3 shows a torque-angle curve increasing logarithmically with respect to a typical operating angle required by a grill shutter actuator. FIG. 4 is an illustration of an assembled actuator according to a preferred embodiment, with the cover removed. 1 shows a gear train configuration of an actuator of a preferred embodiment. FIG. 4 shows a vehicle grill shutter assembly incorporating the actuator of FIG. 3 with the louver in the closing direction. FIG. 6 is the grill shutter assembly of FIG. 5 with the louver in the fully open direction. FIG. 2 is a partially exploded view of a vehicle grill shutter assembly having two louver sets.

  1 and 2 show examples of required grill shutter actuator output torque with an integral return spring for fail-safe operation. FIG. 1 shows a torque-position curve for a system having a linear relationship between the output position (operating angle) of a louver or actuator and the required torque. FIG. 2 is a similar graph, but the system has a logarithmic relationship. In addition to the nearly constant mechanical friction offset, the actuator must overcome the torque that increases with increasing operating angle by the return spring. Further, the force applied to the actuator changes according to the operating angle due to the air pressure on the louver.

  FIG. 3 shows the preferred actuator in its assembled form, with the cover removed so that the interior is visible. The actuator 10 has a casing 12 with a lid (not shown) that houses a stepping motor 20, an output 18 and a gear train 30 that couples the motor to the output. The electric socket 14 can connect a power line and a signal line for operating the motor. Further, a PCB 16 (printed circuit board) related to electronic equipment for controlling the motor based on a command via the signal line is provided. The PCB may include LIN bus electronics for communicating with the engine management computer.

  The gear train 30 is clearly shown in FIG. The gear train couples the motor shaft 22 to the actuator output 18. A preferred embodiment motor is a stepper motor 20, shown in FIG. 4, connected to PCB 16. In the preferred embodiment, the actuator output 18 is a shaft 50 and has a socket, i.e. a star socket 52 that houses the end of the operating shaft of the grill shutter mechanism for changing the angle of the louvers. doing.

  The gear train 30 includes a first spur gear 32 that meshes with teeth 24 attached to the motor shaft 22, a second spur gear 34 that meshes with the first spur gear, a first forward transmission gear 36, and a second forward feed. A transmission gear 38 is provided. The first forward transmission gear is a combination of an ordinary (regular) spur gear 40 and a first helical gear 42. The spur gear 40 meshes with the second spur gear 34, and the first helical gear 42 meshes with the second progressive transmission gear 38. The second progressive speed change gear includes a second helical gear 44 attached to the output shaft of the actuator. The second helical gear 44 meshes with the first helical gear 42.

  The return spring 54 is preferably attached to the output shaft 50 via the second torsion gear 44, and is adapted to return the output shaft to a fixed position or initial operating angle when the motor is turned off. Drive the motor back through. The return spring 54 is shown as a helical spring or a coil spring disposed around the output shaft 50, and one end is fixed to the shaft passing through the second helical gear 44 and the other end is fixed to the casing 12. Therefore, in use, when the output shaft moves from a fixed position, the spring is wound up (or released) and generates an elastic restoring force that biases the output shaft to return to the fixed position. The motor 20 needs to drive the output shaft against this restoring force. Further, the motor needs to drive or hold the output shaft at a desired operating angle against an external force. For example, the external force is applied to the louver by air pressure particularly when the vehicle moves at a high speed such as driving on a highway. It is power.

  The forward transmission gear ratio results from the interaction of the two helical gears. Preferably, the torsion gears 42 and 44 are logarithmic gears whose pitch lines follow a logarithmic spiral track. In the forward gear ratio, the maximum output torque of the actuator changes at various operating angles. This allows the motor to be physically small and allows the desired maximum torque output with a high gear ratio in the high torque demand region, but allows a fast response time due to the low gear ratio in the low torque demand region. . Therefore, the output torque of the actuator more closely matches the load demand, and the motor does not become overpowered at most operating angles, but satisfies the torque demand at a specific operating angle.

  The forward transmission gear may include at least one gear that varies in radius as a function of angle and transmits variable torque and variable tangential speed. In order for the gear to constitute a gear train having a fixed shaft, one advantageous configuration comprises two logarithmic spiral gears that satisfy the following conditions:

-The distance between the two gear shafts is constant.
• The gears make continuous contact during one full cycle.
The radius becomes logarithmically larger than the wheel angle, r (φ) = a · exp (k · φ).
The ratio between the input wheel angle and the output wheel angle is logarithmic (also applies to torque).

  The appropriate magnitude of the torsional gear parameter allows variable torque compensation. By using the progressive gear, the motor size can be remarkably reduced (low cost and light weight), and the average power consumption can be reduced.

  5 and 6 are schematic views of an exemplary grill shutter assembly 60 incorporating the actuator 10 of FIG. The grill shutter assembly has a frame 62 and a plurality of louvers 64 pivotally coupled to the frame. In FIG. 5, the louver is in the closed direction and prevents air flow through the frame, and in FIG. 6, the louver is in the fully open direction to allow maximum air flow. As can be seen from FIG. 6, since the louvers are connected by a cross bar 66, the directions of the louvers are aligned and the louvers move together. The actuator 10 is coupled to the central louver by an operating shaft so as to control the direction of the louver.

  FIG. 7 is a partially exploded view of a grill shutter assembly having two louver sets driven by a single actuator. There are two frames 62 that pivotally support each set of louvers 64. Each frame is placed side by side, and the actuators are placed between them, attached directly to one frame or attached separately. The actuator 10 is connected to each set of louvers by an actuation shaft 68. Each operating shaft 68 is connected to the output shaft 50 of the actuator by being connected to a socket 52 formed at each end of the output shaft 50. Preferably, the shape of the socket and the shape of the end of the actuating shaft are complementary, in particular a star shape, and the connection can be made simply by insertion.

  In use, the louvers are placed in an air flow path leading to one or more heat exchangers such as engine compartments, in particular engine coolant radiators and air conditioning system condensers. The louvers allow air to flow to the heat exchanger when necessary and prevent air flow when cooling air is not needed. In general, the cooling air requirement is significantly reduced during highway driving, and in this mode the louver is closed to close the air intake and improve the vehicle's aerodynamics, thus significantly improving fuel economy. Is done. If the air intake is closed when the vehicle is cold, the warm-up time of the engine, that is, the time until the normal operating temperature is reached, is significantly shortened. This also allows the engine to operate more efficiently and cleanly at normal operating temperatures, thus reducing fuel consumption and pollution.

  In the description and claims of the present invention, the verbs “comprising”, “including”, “including”, and “having” and their derivatives are generic to identify that the item being described exists. It is used in a sense and does not exclude the presence of additional items.

  Although the present invention has been described with reference to one or more preferred embodiments, those skilled in the art will recognize that various modifications are possible. Accordingly, the scope of the invention should be determined by the claims.

  For example, although the actuator is described as having a housing, the motor, gear train, and output shaft can be secured directly to or supported by structural components of the grill shutter assembly, such as a frame.

10 Actuator 12 Casing 14 Electrical socket 16 PCB (Printed Circuit Board)
18 Output unit 20 Stepping motor 22 Motor shaft (shaft)
24 teeth 30 gear train (gear train)
32 First spur gear
34 Second spur gear
36 First progressive gear (progressive gear)
38 Second progressive transmission gear (progressive gear)
40 Spur gear 42 First helical gear (spiral gear wheel)
44 Second helical gear (spiral gear wheel)
50 shafts
52 Socket 54 Return spring
60 Grill shutter assembly
62 Frame 64 Louver 66 Cross bar 68 Operating shaft (shaft)

Claims (11)

An actuator for a vehicle grill shutter assembly comprising:
The actuator is
A motor having a motor shaft;
An output portion including an output shaft and a connecting portion for connecting to the louver of the grille shutter assembly; and a gear train connecting the motor shaft to the output shaft. The gear train includes the output An actuator having a variable gear ratio according to an operating angle of a shaft.   The actuator of claim 1, wherein the gear train comprises at least one progressive transmission gear.   The actuator according to claim 2, wherein the progressive transmission gear includes a first helical gear and a second helical gear meshing with the first helical gear.   The actuator according to claim 3, wherein the second helical gear is attached to the output shaft.   The actuator according to claim 3 or 4, wherein the first helical gear is connected to the motor shaft by at least one spur gear.   The actuator according to claim 3, wherein the first helical gear and the second helical gear have logarithmic pitch trajectories.   The actuator according to any one of claims 1 to 6, further comprising a return spring configured to elastically return the output shaft to an initial operating angle when the motor is inoperative.   The return spring is a coil spring disposed around the output shaft, the first end is fixed to the second torsion gear, and the second end is fixed to the support portion of the output shaft. The actuator according to claim 7.   The actuator according to any one of claims 1 to 8, wherein the motor is a stepping motor and is connected to a PCB having a control circuit for controlling the motor in response to a control signal.   The actuator according to claim 1, wherein the output unit includes two output shafts.   The actuator according to claim 10, wherein the coupling portion includes an output shaft or a non-circular socket formed at an end portion of each output shaft, and is configured to receive an end portion of a corresponding operation shaft of the louver.

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